1. Field of the Invention
The present invention relates to driving apparatus and method for an image scanning and/or forming machine, such as an office machine including a facsimile machine, a laser printer, etc., and more particularly, to driving apparatus and method for an office machine capable of arranging front ends of sheets of paper or documents without using an extra reverse rotation prevention member or an extra power transfer member, such as a swing gear, thereby preventing a paper skew.
2. Description of the Related Art
In general, an office machine, such as a facsimile machine, a multi-function machine, etc., has a scanning device scanning data recorded on documents, a facsimile device transferring or receiving scanned data through communication lines, and a printing device printing the scanned data, the data received through the communication lines, or data inputted from a computer on sheets of paper as an output. The scanning device, which is one of constituents of the office machine, is essentially required to transfer the data recorded on the documents or print the data on the sheets of paper as the output.
FIG. 1 shows a scanning device 10 applied to a general facsimile machine. The scanning device 10 includes a document supply unit 13 formed on an upper side of an apparatus to automatically supply sheets of documents D to be picked sheet by sheet, a scanner 18 reading data from the documents D delivered from the document supply unit 13, and a document discharge unit 21 discharging the documents D passing through the scanner 18 outside the apparatus.
The document supply unit 13 supplying the documents D inside the scanning device 10 is provided with a document supply tray 15 loaded with the documents D, a document sensor 1 detecting whether the documents D is loaded, a pickup roller 14 picking up the documents D according to operations of the document sensor 1, a friction pad 16 being in contact with the pickup roller 14 with a predetermined pressure to separate the documents D sheet by sheet, and a feed roller 14′ conveying the documents D toward the scanner 18.
The scanner 18 includes a contact image sensor 19 reading data from the documents D delivered by a rotation force of the feed roller 14′, and a white roller 20 bringing the documents D to be in contact with the contact image sensor 19.
The document discharge unit 21 has a document discharge roller 22 discharging the documents D, and a document discharge backup roller 23 coming in contact with the document discharge roller 22 with a predetermined pressure.
Further, the scanning device 10 includes a driving unit driving the pickup roller 14, feed roller 14′, white roller 20, and document discharge roller 22.
The driving unit has a driving motor 5 rotating in both directions, a swing gear train 7 switching power of the driving motor 5, a first driving gear 11 meshing with a second swing gear 9 of the swing gear train 7 by the swing gear train 7 rotating in a direction of arrow A about a first swing gear 8 thereof when the driving motor 5 rotates in a clockwise direction as shown in a direction indicated in a solid line arrow of FIG. 1, a feed roller gear (not shown) connected with the first driving gear 11 through a first idle gear 12 and coaxially formed with the feed roller 14′, a pickup roller gear (not shown) connected to the feed roller gear through a second idle gear 24 and coaxially formed with the pickup roller 14, a second driving gear 26 meshing with a third swing gear 25 of the swing gear train 7 by the swing gear train 7 rotating in the direction of an arrow A about the first swing gear 8 thereof when the driving motor 5 rotates in a counterclockwise direction as shown in a direction indicated in a dotted line arrow of FIG. 1, a white roller gear (not shown) connected to the second driving gear 26 through a third idle gear 27 and coaxially formed with the white roller 20, and a document discharge roller gear (not shown) connected to the second driving gear 26 and coaxially formed with the document discharge roller 22.
Operations of the conventional scanning device 10 structured above are described with reference to FIG. 1.
First, when a document D is loaded in the document supply tray 15 to convey or photocopy the document D, the document D slides down due to its weight to operate the document sensor 1. Accordingly, a controller applies electric power to the driving motor 5 to rotate the driving motor 5 in one direction, for example, in the clockwise direction as shown in the solid line arrow of FIG. 1.
As the driving motor 5 rotates in the clockwise direction, the swing gear train 7 rotates in the direction of arrow A, that is, in the counterclockwise direction about the first swing gear 8 thereof to have the second swing gear 9 of the swing gear train 7 to mesh with the first driving gear 11.
Accordingly, the feed roller 14′, which is associated with the first driving gear 11, the first idle gear 12, and the feed roller gear (not shown), rotates in the counterclockwise direction, so does the pickup roller 14 associated with the feed roller 14′ through the second idle gear 24 and the pickup roller gear.
Therefore, the pickup roller 14 picks up the documents D sheet by sheet by a friction force with the friction pad 16, and the feed roller 14′ delivers a sheet of documents picked up by the pickup roller 14 toward a scan sensor 17.
After the scan sensor 17 is opened by a front end of the document D when the front end of the document D reaches the white roller 20 with a lapse of a predetermined time, the front end of the document D is arranged in curl by the white roller 20 which is stationary due to a cutoff of a rotation power from the swing gear train 7.
At this state, when a user presses a start button of the facsimile machine conveying or photocopying the document D, the driving motor 5 is driven in a reverse direction, that is, from the clockwise direction to the counterclockwise direction, by which the swing gear train 7 rotates in the direction of the arrow A, that is, in the clockwise direction about the first swing gear 8, and the third swing gear 25 of the swing gear train 7 is meshed with the second driving gear 26.
Accordingly, the white roller 20, which is associated with the second driving gear 26, the third idle gear 27, and the white roller gear (not shown), rotates in the clockwise direction, so does the document discharge roller 22 associated with the second driving gear 26 through the document discharge roller gear (not shown).
Therefore, the document D passes through a nip between the contact image sensor 19 and the white roller 20 by the white roller 20, and the contact image sensor 19 of the scanner 18 reads data from the document D.
As stated above, when the contact image sensor 19 of the scanner 18 completely reads out the data from the document D, the document D is discharged outside the apparatus by the document discharge roller 22.
However, the conventional scanning device 10 as described above should use a power switching member or a reverse rotation prevention member, such as the swing gear train 7 including three swing gears 8, 9, and 25 to have the white roller 20 stationary without movements so that the front ends of the documents D are arranged while preventing the documents D from being skewed, when the power of the driving motor 5 is transferred to the pickup roller 14 and the feed roller 14′. Accordingly, a problem occurs that a structure of the driving unit of the scanning device 10 becomes complicated and a manufacturing cost increases.
Further, the use of the swing gear train 7 causes a structure of the second and third swing gears 9 and 25 to move by a coupling force upon power switching operations of the driving motor 5, which generates noise as well as vibrations or malfunctions due to irregular operations. Accordingly, jitter occurs on a final image obtained upon photocopying or conveying, or a document jam occurs, and the jitter or the document jam causes a problem that lowers the product reliability.
Furthermore, when the switching gear train 7 is switched by the driving motor 5, it takes time to mesh the second and third swing gears 9 and 25 with the first and second driving gears 11 and 26 so that time for readout of the documents becomes prolonged, which causes a problem that delays photocopying or conveying times.